I believe it is theoretically possible to create a sculpture like this for any group of 3 images - as long as the images have the same dimensions (i.e., their maximum lengths and maximum widths are all equal). Imagine taking a cube, and then drawing each shadow on the faces so that opposite faces have images that line up. You would also need to require that each image touch all four edges of the face. Then, just cut all the excess off. It's hard to picture but I'm pretty sure that would do the trick.
However, if you notice how the sculpture is rotated in the video, it is pretty clear that this isn't the method that the artist uses. If he used the method I described, there would be no axis through the sculpture through which you could project each shadow. So I am at a loss as to how he did it. It's pretty cool.
Edit: Actually I pictured it in my head wrong. The process I described is exactly how he did it. Had to grab a kleenex box and rotate it around to figure it out haha :)